Today we are going to do the Frequently Asked Questions of what is the difference between a three wire system and a two wire system. It is actually very easy and very simple. All it is, is you take away two wires and the same thing applies to the four and five wire system. Starting off on the car side we are going to attach the wiring to, we are going to have five wires. Green is going to be right turn, red is going to be the brake signal, yellow is going to be left turn, brown is going to be your running lights, and the white is going to be ground. When you talk about the three wire system you are only talking about the right turn, the brake signal, and the left turn. You omit the brown wire and the white wire. That is our three. On the two wire system you are only dealing with the two combined signals, the brake signal and the turn signal on the same wire. We are only dealing with the left and right turn. 00:46
Next we will show a couple of examples of a two wire system compared to a three wire system. First we are going to show you a version of a two wire system. We are going to use my little truck and we are going to show the turn signal first and then we will stop that and we will turn on the brake signal. I have got my left turn signal on and now hit the brake and you see the actual same bulb turns on. That tells you that it is a combined system. In this vehicle it is going to be very easy to see that we have a three wire system. First off we have got the yellow turn signal to tell us right away that is going to be a separate system. Yellow is going to be the turn signal and the red on the bottom is going to be our brake light. Just to reiterate we will turn on our turn signal and then we will hit the brake signal and you can see the difference so that means we have got a three wire system.
Today on our 2005 Chevy Silverado, we are going to hook up the hot lead for the seven pull connecter at the back of the truck. To do this well simply remove the fuse box cover and the first position, on the first row is a blank fuse, we are going to remove it and install a 30 amp fuse. With that fuse installed, we can go ahead and replace the cover and were now hot at our seven pull connector. There you have it with the install of the hot lead fuse on our 2005 Chevy Silverado.
Today we are going to troubleshoot a modulite that is not really working so we will check it out and show you what to look for. This will apply to all modulites and this will also apply to converter boxes as well. The only difference being that it does not have a power wire for a converter box. The first thing we want to do is put a tester on the 4-pole just to make sure. We will hook up our ground to our ground lead and then we will turn on the left turn signal which we have going, we have got nothing. You can turn on the other signals and see what we have got, nothing here. Try the running light circuit, nothing here either. 00:28
All right today we are going to go over how to check over a modulite as shown right here which converts a 5 wire to a 4 wire system. We are going to go over the basics which are really simple. Basically we are just going to test input into the modulite and test the output of the modulite. That will tell us one of two things, we have no input going into the modulite, that means there is something wrong on the car side of the connector, there is nothing wrong with the modulite. If you have power going into it, but nothing coming out then you know chances are it is the modulite or there is a problem on the trailer itself. When testing you always want to test these modulites or converter boxes without the trailer hooked up first.
Today we are going to cover kind of a different subject. Basically, we are going to talk about getting your wiring installed and what is happening afterward. Okay, for instance, you went to the trouble to get your wiring installed, you plug it into your trailer, and nothing happens. There could be a lot of different things going on with it. First off, you need to figure out for sure whether it is on the towing vehicle side - the car or truck - or if it is something on the trailer. We will show you how to test the different types of wiring systems we have shown here. And that way you can tell for sure if it is your wiring harness or if it is your trailer.
Today we are going to show you a little bit of wiring. Basically kind of like wiring 101 and what to look for when your going to hardwire into the vehicle. What hardwire means is actually getting to the wire and splicing into them to make a connection. T1 connectors are different. They actually have a connection point and harness which you take apart and fit the T in the middle of that. Now on this vehicle we will show you the typical wiring schematics and a couple variants from that. The typical connection point is like where this wiring comes into the back of the tail light and there is always going to be a connection point, almost always. Older vehicles, it would have just ran straight, but with pretty much of your newer vehicles you are always going to have a snap connection like this. Basically a T1 connector simply would just go ahead and fit in between this harness.